Psychiatric diseases and disorders (also referred to as mental illnesses or disorders) are described in resources such as the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). Broad categories of mental disorders include, but are not limited to, mood disorders, anxiety disorders, schizophrenia and other psychotic disorders, substance-related disorders, sleep disorders, somatoform disorders, and eating disorders. Examples of mood disorders include bipolar and depression. Other conditions falling within the broader category of disorders described above can be found in the DSM-IV, which is incorporated by reference in its entirety and for all purposes. These are debilitating illnesses that affect millions of people and involve astronomical costs, in terms of treatment, lost productivity, and emotional toll.
In 2001, the National Institute of Mental Health published a summary of statistics describing the prevalence of mental disorders in America. In the report, it estimated that 22.1% of Americans ages 18 and older suffer from a diagnosable mental disorder in a given year (Reiger et al., 1993, Archives of General Psychiatry 50:85-94). When applied to the 1998 U.S. Census, the number of people affected was 44.3 million.
Depressive disorders can encompass, among others illnesses, major depressive disorder, dysthymic disorder and bipolar disorder. About 9 to 9.5 percent of the U.S. population ages 18 and older have a depressive condition. It has been reported that the direct cost of depressive disorders is about $80 billion, with two-thirds of it being borne by businesses. The indirect costs associated with depressive disorders, such as lost productivity, are harder to calculate because of events such as “presenteeism,” described as people at work but limited in their ability to produce or participate (Durso, Employee Benefit News, December, 2004).
Another psychiatric condition is anxiety disorders. These disorders can include panic disorder, obsessive-compulsive disorder, post-traumatic stress disorder generalized anxiety disorder, and phobias. Approximately 19.1 million American adults ages 18 to 54 (about 13.3% of people in this age group in a given year) have an anxiety disorder.
Another common psychiatric condition is eating disorders. There are three main types, anorexia nervosa, bulimia nervosa, and binge-eating disorders. These psychiatric conditions are often linked to perceived notions relating to body image and are usually independent of actual body weight or body mass index. The mortality of people with anorexia has been estimated at 0.56 percent per year, or approximately 5.6 percent per decade, which is about 12 times higher than the annual death rate due to all causes of death among females ages 15-24 in the general population (Sullivan, 1995, American Journal of Psychiatry 152:1073-1074). It should be noted that psychiatric illnesses usually present with elements of other psychiatric disorders.
Another psychiatric condition is schizophrenia. In a given year, over 2 million people are clinically diagnosed with schizophrenia, and there is a lifetime prevalence of this disease in approximately 1% of the U.S. population. Schizophrenia is a chronic, debilitating disease that leaves an estimated 75% of treated patients without ever achieving complete recovery. Treatment of schizophrenia with the newer (atypical) antipsychotic medications frequently comes with the side effect of weight gain and possibly diabetes.
Exemplary types of schizophrenia include paranoid schizophrenia. These persons are very suspicious of others and often have grand schemes of persecution at the root of their behavior. Hallucinations, and more frequently delusions, are a prominent and common part of the illness. Persons with disorganized schizophrenia (hebephrenic schizophrenia) are verbally incoherent and may have moods and emotions that are not appropriate to the situation. Hallucinations are not usually present with disorganized schizophrenia. Catatonic schizophrenia describes where a person is extremely withdrawn, negative and isolated, and has marked psychomotor disturbances. Residual schizophrenia describes where a person is not currently suffering from delusions, hallucinations, or disorganized speech and behavior, but lacks motivation and interest in day-to-day living. Schizoaffective disorder describes where a person has symptoms of schizophrenia as well as mood disorder such as major depression, bipolar mania, or mixed mania. Undifferentiated schizophrenia describes where conditions meet the general diagnostic criteria for schizophrenia but do not conform to any of the above subtypes, or there are features of more than one of the subtypes without a clear predominance of a particular set of diagnostic characteristics.
Psychiatric diseases and disorders can be found in any age group. Accordingly, these disorders can be found in young adults and adults (defined herein as those aged 65 or under) as well as infants, children, adolescents, and the elderly (defined herein as over the age of 65). In fact, certain segments of the population may be particularly prone to having a condition, such as eating disorders in adolescents and young adults. The elderly may be particularly susceptible to conditions such as depression.
Current treatments include psychosocial and behavioral therapy, electroconvulsive therapy, and/or medication. A common form of treatment for psychiatric illnesses, or at least a component of the treatment, is the administration of medication. A need remains for new and/or improved molecules and medications effective to treat psychiatric diseases and disorders. In addition, needed are molecules that effectively treat those patients resistant to the current medications, effectively treat psychiatric diseases or disorders without the unwanted side effects of the current medications, have a faster onset of therapeutic action, and/or improve physical co-morbidities (e.g., diabetes, pain, weight gain) that often present with and make more difficult the treatment of psychiatric illnesses.
All references cited herein are incorporated by reference in their entirety and for all purposes.